Java is among the most popular worldwide used programming languages, which is known for its reliability and extensive use in web and software development. For those who are gearing up for coding interviews, technical assessments, or simply want to revise your understanding, solving Java MCQ questions and answers may be the best technique. Here, you will get to know about 50 Java MCQs with topics like Object-Oriented Programming (OOP), Multi-threading, Exception handling, and other advanced Java topics. These questions are intended as a useful tool for enhancing your knowledge of the basic concepts in Java and for preparing for various assessments.
55 Java MCQ Questions and Answers to Boost Your Programming Knowledge
Mastering Java becomes easier when you regularly practice multiple-choice questions. These 50 Java MCQ questions and answers will help you test and strengthen your understanding of essential Java concepts, ranging from basic syntax to more advanced topics such as multithreading and exception handling.
- What does JDK stand for?
a) Java Development Kit
b) Java Deployment Kit
c) JavaScript Development Kit
d) None of these
Answer: a) Java Development Kit
- JRE stands for ___?
a) Java Runtime Ecosystem
b) JDK Runtime Environment
c) Java Runtime Environment
d) None of these
Answer: c) Java Runtime Environment
- What makes Java platform-independent?
a) Advanced programming language
b) It uses bytecode for execution
c) Class compilation
d) All of these
Answer: b) It uses bytecode for execution
- Who invented Java Programming?
a) James Gosling
b) Dennis Ritchie
c) Bjarne Stroustrup
d) Tim Berners-Lee
Answer: a) James Gosling
- Which method is used to compare two strings for equality?
a) ==
b) equals()
c) compare()
d) isEqual()
Answer: b) equals()
- Which of the following is a valid syntax to synchronize a HashMap?
a) Map m = hashMap.synchronizeMap();
b) HashMap map = hashMap.synchronizeMap();
c) Map m1 = Collections.synchronizedMap(hashMap);
d) Map m2 = Collection.synchronizeMap(hashMap);
Answer: c) Map m1 = Collections.synchronizedmap(hashMap);
- What is the default capacity of an ArrayList?
a) 5
b) 10
c) 0
d) 100
Answer: b) 10
- Which of the following is a mutable class in Java?
a) java.lang.String
b) java.lang.Byte
c) java.lang.Short
d) java.lang.StringBuilder
Answer: d) java.lang.StringBuilder
- What is the correct way to declare a comment in Java?
a) //
b) /* */
c) <!– –>
d) All of these
Answer: b) /* */
- Which method is used to find the length of a string?
a) size()
b) length()
c) getLength()
d) len()
Answer: b) length()
- What is polymorphism in Java?
a) Single form
b) Multiple forms
c) Static form
d) No form
Answer: b) Multiple forms
- What is encapsulation in Java?
a) The process of combining data and methods into a single unit
b) Hiding data and methods within a class
c) Creating multiple instances of a class
d) Reusing code from existing classes
Answer: a) Combining data and methods into a single unit
- Which method in Java is used to compare objects?
a) ==
b) compare()
c) equals()
d) compareTo()
Answer: c) equals()
- What is inheritance in Java?
a) Reusing code from existing classes
b) Hiding data and methods within a class
c) Creating multiple instances of a class
d) Combining data and methods into a single unit
Answer: a) Reusing code from existing classes
- What does the super keyword do in Java?
a) Refers to the current object
b) Invokes the superclass constructor or methods
c) Creates multiple instances of a class
d) Hides data and methods within a class
Answer: b) Invokes the superclass constructor or methods
- What is meant by the classes and objects that depend on each other?
a) Tight coupling
b) Loose coupling
c) Strong encapsulation
d) Weak encapsulation
Answer: a) Tight coupling
- What is meant by abstract classes in Java?
a) Classes that cannot be instantiated
b) Classes used as blueprints for objects
c) Classes that contain abstract methods only
d) All of the above
Answer: d) All of the above
- What is the purpose of the this keyword in Java?
a) Refers to the current object
b) Refers to the superclass
c) Creates an instance of the class
d) Declares a new class
Answer: a) Refers to the current object
- What is method overloading in Java?
a) Creating multiple methods with the same name but different parameters
b) Creating multiple methods with the same name and parameters
c) Declaring multiple methods in a single class
d) None of the above
Answer: a) Creating multiple methods with the same name but different parameters
- Which keyword is used to define a constant variable in Java?
a) constant
b) static
c) final
d) const
Answer: c) final
- What is the main purpose of multithreading in Java?
a) To divide tasks among multiple threads
b) To manage a single thread
c) To minimize memory usage
d) To increase the program execution time
Answer: a) To divide tasks among multiple threads
- Which Java class is thread-safe?
a) StringBuilder
b) StringBuffer
c) ArrayList
d) LinkedList
Answer: b) StringBuffer
- What is the role of the synchronized keyword?
a) It controls thread access to shared resources
b) It enhances garbage collection
c) It manages memory allocation
d) It compiles the code
Answer: a) Controls thread access to shared resources
- What is the wait() method used for in multithreading?
a) To stop a thread
b) To pause the execution of a thread until another thread signals
c) To terminate the thread
d) To start the thread
Answer: b) To pause the execution of a thread until another thread signals
- Which method is used to start a thread?
a) run()
b) start()
c) execute()
d) begin()
Answer: b) start()
- Which exception is thrown when a thread is interrupted?
a) ThreadException
b) InterruptedException
c) ExecutionException
d) IOException
Answer: b) InterruptedException
- What is exception handling in Java?
a) Managing errors during execution
b) Optimizing Java code
c) Declaring variables
d) Formatting output
Answer: a) Managing errors during execution
- What is the difference between throw and throws?
a) throw is used for declaring exceptions, throws is used to throw exceptions
b) throw is used to throw exceptions, throws declares exceptions
c) Both are used interchangeably
d) None of the above
Answer: b) throw is used to throw exceptions, throws declares exceptions
- Which block in Java is always executed, even if no exception is thrown?
a) try
b) catch
c) finally
d) throw
Answer: c) finally
- What is the superclass of all exceptions in Java?
a) Throwable
b) Exception
c) RuntimeException
d) Error
Answer: a) Throwable
- What is the use of the transient keyword?
a) To make a variable non-serializable
b) To make a method run faster
c) To prevent variable modification
d) To remove variable from memory
Answer: a) To make a variable non-serializable
- Which collection class allows only unique elements?
a) ArrayList
b) LinkedList
c) HashSet
d) Vector
Answer: c) HashSet
- Which of the following methods are part of the Object class?
a) notify(), wait(), and notifyAll()
b) sleep(), wait(), and notify()
c) run(), start(), and wait()
d) notify(), stop(), and start()
Answer: a) notify(), wait(), and notifyAll()
- What is the default value of a boolean variable?
a) true
b) false
c) null
d) 0
Answer: b) false
- Which data type is used to create a variable that stores text in Java?
a) String
b) char
c) boolean
d) int
Answer: a) String
- Which keyword is used to prevent inheritance of a class?
a) static
b) const
c) final
d) private
Answer: c) final
- Which method must be implemented by all threads?
a) stop()
b) start()
c) run()
d) wait()
Answer: c) run()
- What will happen if you invoke the start() method twice on the same thread object?
a) The thread will run twice
b) The thread will stop immediately
c) It will throw an IllegalThreadStateException
d) It will cause a deadlock
Answer: c) It will throw an IllegalThreadStateException
- What is the role of the finally block in Java?
a) It executes after the try block only when an exception occurs
b) It is executed whether an exception occurs or not
c) It is used to handle all exceptions
d) It is optional and can be ignored
Answer: b) It is executed whether an exception occurs or not
- Which of the following is a checked exception in Java?
a) NullPointerException
b) IOException
c) ArithmeticException
d) ArrayIndexOutOfBoundsException
Answer: b) IOException
- What is the result of 5 + 2 + “3” in Java?
a) 73
b) 523
c) 33
d) 7
Answer: a) 73
- Which keyword is used to inherit a class in Java?
a) super
b) implements
c) extends
d) inherits
Answer: c) extends
- What is the default value of an int variable in Java?
a) 0
b) null
c) 1
d) -1
Answer: a) 0
- Which method is used to terminate a Java program?
a) exit()
b) stop()
c) System.exit()
d) terminate()
Answer: c) System.exit()
- What is the result of 10 / 3 in Java?
a) 3.33
b) 3
c) 3.0
d) Compile-time error
Answer: b) 3
- Which of the following is not a Java access modifier?
a) public
b) private
c) protected
d) default
Answer: d) default
- What does the final keyword mean in Java?
a) The variable is constant and cannot be changed
b) The class can be inherited
c) The method can be overridden
d) The object can be modified
Answer: a) The variable is constant and cannot be changed
- Which of these operators is used to allocate memory for an object in Java?
a) malloc
b) new
c) create
d) allocate
Answer: b) new
- What is the output of System.out.println(“Java” + 10 + 20);?
a) Java1020
b) 30Java
c) Java30
d) Java2010
Answer: a) Java1020
- Which package contains the String class?
a) java.util
b) java.io
c) java.lang
d) java.sql
Answer: c) java.lang
- Which of the following cannot be used for a constructor in Java?
a) public
b) private
c) static
d) protected
Answer: c) static
- How can we prevent a class from being inherited in Java?
a) By using the final keyword
b) By using the static keyword
c) By using the abstract keyword
d) By using the protected keyword
Answer: a) By using the final keyword
- Which of the following methods is used to terminate a thread?
a) `exit()`
b) `terminate()`
c) `stop()`
d) `kill()` – *
Answer: c) `stop()`
- Which of the following is used to perform garbage collection in Java?
a) System.gc()
b) Runtime.getRuntime().gc()
c) Both a and b
d) None of the above
Answer: c) Both a and b
- How do you restrict a variable in a class to be accessed by only methods within the same class?
a) public
b) protected
c) private
d) default
Answer: c) private
FAQs
Q1. How can Java MCQ questions and answers help in interview preparation?
Java MCQ questions and answers help gain more understanding of different Java concepts and ideas. They enable you to easily revise some of the most important topics like OOP, data structures, multithreading, or exception handling which are commonly asked in the interviews. By doing practice often, you increase your speed in answering questions and you feel more comfortable when being interviewed.
Q2. What are the common topics covered in Java MCQ questions?
Java basics including data types and control statements, object-oriented programming (OOP) principles, collections, multi-threading, exception handling, and file and I/O operations. are some of the frequently taught concepts. additionally, special concepts such as JVM, garbage collection, and Java frameworks are also included.
Q3. Are Java MCQs enough to fully master Java programming?
Java MCQ questions and answers provide a solid foundation and are helpful for quick learning, mastering Java requires hands-on coding experience. However, it is not enough to master Java it is important to write and debug code to get the practical implications of the concepts shown in the book.
Q4. Where can I find Java MCQ questions and answers for practice?
Java Multiple Choice Questions & Answers are available in different resources such as educational websites, forums, and coding practice websites. They are often provided with solutions to help the students understand the right answers and improve your conceptual clarity.
Q5. How often should I practice Java MCQs to stay sharp?
It’s important to practice Java MCQs as frequently as possible, especially if you’re preparing for an interview or exam. Even 30 minutes a day can make a significant difference in shaping your knowledge and boosting your confidence.
Wrapping Up
Solving Java MCQ questions and answers will help you improve your knowledge of the fundamentals of Java programming. From basic syntax to more advanced topics like multithreading and exception handling, these questions provide a structured and engaging way to prepare for technical interviews and exams. Regular practice not only enhances your problem-solving abilities but also helps you stay updated with the latest Java concepts. Just continue practicing and you will be able to understand Java programming well.